LLY: LLY has a rev limiter,

[Duramax junkie]

I have an 05 Chevy 2500HD crewcab ,longbed 4X4 with the 6.6 LLY Diesel , I bought the motor was apart," front left corner" I have put together and it runs pretty good, 255K on it, problem is it will start and run normal for about 3 minutes,, it will shift all gears, and run down the road, then it happens, the motor will not rev over 2100 RPM, it is not in LIMP mode, I can let off the fuel ,it will shift up thru all gears, will run 65-70 MPH, message board on dash says " change fuel filter ". running down the road if you stomp on it, it will shut down like its starving for fuel, runs great at the start , will smoke the tires, till the limit hits, I've changed fuel filters 3 times now, including today, got 3 minutes out of it , and the 2100RPM is back, if you shut it down for 5 minutes it will run like it should for 2-3 minutes, and back to 2100RPM, I'm changing the fuel/water separator sending unit in the morning with the hope that the float has a hole and is being pushed up and plugging the filter passage, any and all help would be greatly welcomed, thanks in advance

 

[Robby05]

Look over all the fuel lines from the tank to the engine. Probably I've some sections of rubber hose that need replaced.

 

[2004LB7]

2x

Double check all the rubber fuel lines running up to the CP3. Any old cracked,etc line should be replaced. One of them may be collapsing and causing a fuel restriction. Also it could be getting air in the line. May need to rebuild the filter housing

 

[Duramax junkie]

UPDATE , Major fuel leak

Took truck in town, came out of store ( left running) large fuel spot on ground, drove home , lost over a 1/4 tank of fuel coming home Approx 10 Miles. found fuel running down left side rear of motor under the fuel rail and off back of motor . tore apart found no bad lines or hoses. is there a pressure relief valve in the end of the fuel rail, only place I can find that might be leaking in that area.

 

[dirtydmax]

Took truck in town, came out of store ( left running) large fuel spot on ground, drove home , lost over a 1/4 tank of fuel coming home Approx 10 Miles. found fuel running down left side rear of motor under the fuel rail and off back of motor . tore apart found no bad lines or hoses. is there a pressure relief valve in the end of the fuel rail, only place I can find that might be leaking in that area.

Any fuel under or around the cp3?

 

[clrussell]

Took truck in town, came out of store ( left running) large fuel spot on ground, drove home , lost over a 1/4 tank of fuel coming home Approx 10 Miles. found fuel running down left side rear of motor under the fuel rail and off back of motor . tore apart found no bad lines or hoses. is there a pressure relief valve in the end of the fuel rail, only place I can find that might be leaking in that area.

Id bet you have a high pressure line or return line leaking.. Put it together and start it up while looking for leaks

 

[Elgavilan]

There is a pressure relief valve in the back end of the drivers side fuel rail. It is sealed with an oring and they can leak. They are usually very tight and take a cheater bar or breaker bar to bust loose.

Sent from my XT1254 using Tapatalk

 

[Duramax junkie]

thanks for the replies, I checked for leaks all over before tear down, only fuel found was running along top edge passenger side valve cover and the plennum, no rubber lines have holes, not leaking on steel lines, found a resessed torque head plug in the end of Passenger side fuel rail, thought it might be a PRvalve. no fuel in valley under CP3 all dry except along top of valve cover, I did see fuel running along there and down the back of engine and down to the floor. lost massive fuel on ten mile trip home from town so im pretty sure its on the high pressure side

 

[clrussell]

thanks for the replies, I checked for leaks all over before tear down, only fuel found was running along top edge passenger side valve cover and the plennum, no rubber lines have holes, not leaking on steel lines, found a resessed torque head plug in the end of Passenger side fuel rail, thought it might be a PRvalve. no fuel in valley under CP3 all dry except along top of valve cover, I did see fuel running along there and down the back of engine and down to the floor. lost massive fuel on ten mile trip home from town so im pretty sure its on the high pressure side

Tighten the piss out of the high pressure lines to fuel rail.. I've had quite a few Lily's do that after having them apart.